


Pretty Vicious

by wellthatjusthappend



Series: Merfolk AU [3]
Category: Batman - All Media Types
Genre: Blood and Gore, Interspecies Sex, M/M, Other, brief bondage, brief inappropriate touching, contemplation of rape, fluffy jaytim, mermaid au, mermaids are intersex, or merman au I guess, possesive behavior, this is all from Black Mask's perspective so expect some messed up stuff ok, treatment as pet/property
Language: English
Status: Completed
Published: 2017-05-09
Updated: 2017-05-09
Packaged: 2018-10-29 20:51:10
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,406
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10861851
Author URL: https://archiveofourown.org/users/wellthatjusthappend/pseuds/wellthatjusthappend
Summary: Roman Sionis liked to own things that were beautiful and exotic as much as the next crime lord flaunting his power. He liked them even better when they were also dangerous, dark, bloody, and full of contradictions.The moment he saw Jason through the glass of the tank he knew he had to have him.





	Pretty Vicious

**Author's Note:**

  * For [MissNaya](https://archiveofourown.org/users/MissNaya/gifts).



> So I got this idea and thought about sending it to MissNaya. But then it kept getting more and more detailed so I just decided to write it myself :)

“Well, well.... Aren’t _you_ beautiful?” murmured Roman approaching the tank. The container was much too small for the magnificent creature inside. But Roman didn’t really expect much more from non-human traffickers.

“Cost my men an arm and a leg to catch him.” the salesman joked, though from the bandages that Roman had seen on some of those guarding the tank and their wary expressions he suspected that most likely literally true.

It made the creature even more attractive.

“I think I would like to inspect it a little more before I make a decision.” Roman told the man tilting his head to get a better look at the Mer that had cramped itself in the corner of the small tank, long tail blocking most of the view.

“Oh, uh, are you sure?” asked the salesman nervously, Roman turned so the man could feel the weight of his gaze behind the mask… the salesman went pale, “I mean, of course we can Sir. Anything for the Black Mask.”

Roman watched the man scurry off to give orders with more than a little satisfaction.

It became immediately apparent why the salesman had been hesitant. The moment the workers tried to mess with the tank the Mer became violent. By the time the workers managed to shoot a tranquilizing dart into the unarmored skin the water was murky with blood.

Roman licked his teeth behind the mask and flexed his gloved hands.

“Here we are.” said the salesman wearily as they removed the Mer from the tank and began strapping him down to a long table, “We can’t keep it out of the water for too long, but…”

“Can it not breathe air?” asked Roman with interest approaching as the workers finished tying the Mer down.

“All Merfolk can hold their breath for an extraordinary amount of time, but they have to return to the water after a while.” the salesman informed him.

Roman hummed, and ran a gloved hand over the creature’s flank. The long scaled tail was jet black with blood red highlights on its fins. It was hard beneath Roman’s fingers and he had seen first hand the power it could wield. The humanoid top of the creature was light skinned and broad shouldered with defined musculature. There was a dark mop of hair with a single white streak on it’s head and pretty facial features even as it flashed razor sharp bloody teeth at him. Big blue-green eye blazed at him with a fire Roman wouldn’t have expected from a creature of the sea.

“A Mer _man_ then?” asked Roman tapping the creatures flat chest with a gloved hand. He wondered if without his gloves he would be able to feel the rapid pound of the beast’s heart.

“Ah well, if you will,” shrugged the salesman, “The Merfolk are all built for creation or procreation. See?”

The salesman showed Roman a hidden slit in the Mer's scales. The creature snarled at them and twitched in its bonds.

“If aroused in the correct manner, a penis was emerge from here. Alternately, just behind here,” he exposed the slit a little better for Roman to see, “they can be impregnated. Are you thinking of possibly getting another for breeding it later on?”

“Perhaps.” hummed Roman looking back at the pretty face of the creature. It (he?) looked like it was plotting his murder. Roman grinned behind his mask.

“You should be careful about that. Merfolk often kill potential mates if they think they’re not worthy enough.” the salesman told him.

“Do they?” Roman asked stroking the creature's skin just to watch it snarl at him.

“If you’d prefer, I could find you a maid? I know they are more popular-”

“No,” Roman said enjoying the way the Mer was still obviously hostile even as it’s gils on it’s neck began to flutter and flap for water as it’s breath ran out, “No, he’s _perfect.”_

* * *

Roman had his office remodeled so that a huge tank could be fitted to the entirety of one wall. Inside were rock formations riddled with caves and live fish swam about for food. The Merman hid in the caves for the first week or so coming out only to snap up fish. Roman sometimes would catch glimpses of him glaring at him from the shadows, eyes reflective and unnerving for anyone who wasn’t the Black Mask of Gotham city.

From his paperwork, Roman learned that his new pet’s name was Jason.

He also was amused to learn that Jason was quite curious. He never stopped being suspicious of Roman, but he began to slowly emerge to better watch the comings and goings in the office with bright intelligent eyes. Roman privately enjoyed this, especially because Jason tended to make those who visited his office uneasy. There was nothing quite like striking a deal while there was a large, beautiful, monster from the deep swimming behind you.

For a long time Roman didn’t consider using Jason for anything more than his personal viewing pleasure and intimidation for everyone else. But then one day a underling of his was dragged before him. Roman listened as he was informed how this man had raped the daughter of a cop and now a formal investigation was being conducted on one of the clubs he owned. It was going to be costly not just because he hated cops in his business unless they were on his paycheck, but because the cops presence would scare off a lot of customers and thereby revenue.

“You worthless slime,” glared Roman whipping out a gun and pressing it to the sweating man’s temple as rage coursed through his veins. He paused though as he Jason moving in his peripheral vision distracted him. He was swimming around his tank in agitation watching the events in the office with rapt attention. He was revisited by images of clouded water, razor sharp bloody teeth, and the screams of the workers. Roman pulled the gun away from the man’s temple.

“Sir?” asked one of his masked men nervously.

“Drop him in the tank.” Roman said. The men all telegraphed their shock and horror and intrigue even as the convicted man began to weep.

“Please, sir, just shoot me, I beg of you.” he begged.

“You’ve caused me trouble. I don’t like people who make extra work for me. I don’t think you deserve something as kind as a bullet. Now take him out of my sight.” Roman said coldly.

He settled down in his chair to watch as the man began to scream as he was dragged from the room. A moment later he saw the man fall through the surface of the water in the take. He screamed a mouthful of bubbles as he caught sight of Jason. The Merman circled the struggling man like the predator he was and then-

“Beautiful…” Breathed Roman as Jason stuck lightning fast and the water clouded with blood. He watched hungrily as Jason continued his work and the man eventually stopped twitching. He wondered if Jason would eat him, but once the man was mutilated to the Merman’s satisfaction Jason swam off and left the corpse float to the surface.

So powerful. So vicious. So _interesting._

Jason caught sight of Roman watching him and barred his teeth at him at him before darting off to one of his caves.

After that, Roman would often drop the people he wanted dead in Jason’s tank. Not everyone, he still reserved it for people who had really pissed him off and deserved a nasty death. But enough that rumors started about how if you got on Black Mask’s bad side he would feed you alive to his pet monster. This was of course fanatical. Jason never ate any of the human’s he threw in his tank, nor did he ever draw out their deaths obscenely. Roman did nothing to discourage the rumors though, they only helped his reputation to be feared after all.

Roman rewarded special kills with larger food like seals or sharks for Jason to hunt and eat.

Still though, Jason apparently didn’t kill just anyone. Sometimes Roman would throw people in and Jason would throw them back. Granted, the powerful blow with his tail often put them in critical condition anyway, but it still intrigued Roman. For a while he couldn’t discern what determined such a choice. He theorized for a while that perhaps his pet just wasn’t always in a violent mood. However, after a while he discovered that it actually depended on what the doomed people were convicted of. Most were scumbags that Jason saw no problem with killing. If they seemed mostly innocent though he wouldn’t kill them. If they were convicted of something that was not typically kill worthy but they had participated in acts that Jason hadn’t liked in the office then they were killed. If they were convicted where Jason couldn’t see them they were spared. Sometimes only to be killed later if Roman made it clear why they’d been tossed in.

That was how Roman figured out his pet could understand human speech. He could at least read lips. This meant that when Roman and his associates were masked Jason couldn’t understand them. It was a rather useful discovery.

Everything changed though when Batman and Robin raided an event one night.

Roman was smart enough not to try and take on the Bat head on, instead letting his men and hired fighters take the brunt. Somehow though, Robin had broken away from his partner to chase after him. Roman was more than skilled enough to take Robin on his own though. He was cautious and lacking in direct strength unlike most vigilantes. Clever though, and full of nasty little gadgets.

He pissed Roman off.

Spotting the open lid of the tank, Roman grinned darkly to himself and at the next opening grabbed Robin bodily and threw him in. Jason probably wouldn’t kill him directly because he didn’t recognize him, but he’d be at least incapacitated when Jason threw him out. No one escaped that treatment without at least a few broken bones. After another thought, Roman closed the lid of the tank in a little bit of spite.

Let the little bird drown, served him right for getting in the way of Roman’s plans.

With that, he fled before before the Bat inevitably came for his sidekick. Roman ran down to his office to get to the entrance of a secret exit he had accessible from there.

When he got there though he had to pause and stare.

Jason was holding Robin closely and was in a deep lip lock with the boy. It took Roman a moment to realize that Jason wasn’t kissing him but instead breathing air into him. Of course he wouldn’t be, Roman chided himself, kissing was a human tradition that Jason wouldn’t know. Merfolk’s mating practices were more like fights that ended in bloody claiming bites on their necks.

Robin looked shocky, his fingers clenching and unclenching on Jason’s shoulders. Roman’s pet was holding the boy with a gentleness he’d not witnessed or thought possible of the Merman. It was irritating. And fascinating. Roman quickly hid as the lid of the tank was opened and the shadow of the Bat could be made out. Robin immediately pulled back and began to struggle to try and get upward… with absolutely no effect. Roman took small pleasure in how strong his pet was.

Then Jason was swimming them up to the surface and handing Robin into the waiting (trembling) hands of the Bat. Their shadows moved away from the opening and Jason hesitated  before popping his head above the surface to watch them go.

“Sir, the Batman has left. It seemed that he was too concerned for his partner to pursue any further tonight.” One of Roman’s men came running to inform him.

Roman continued to watch Jason at the surface, his long black and red tail swishing back and forth.

“Sir?”

Roman watched as Jason finally couldn’t hold his breath anymore and had to duck back into the water looking frustrated.

“Regroup,” Roman said finally turning to the masked underling, “The Batman may have found us here tonight but has nothing real on us. If he did, the cops would already be swarming us. We have a mole though, see that he’s found. I think he deserves to meet my Jason all nice and personal.”

Hopefully not for the lip-lock of his life. Roman cursed in his head and looked over at Jason who was trying to peek out of the tank again.

“And shut that thing before he bites off someone’s leg.” Roman said jerking his chin towards the tank.

“Yes sir!”

* * *

 

It’s not that Roman didn’t know he couldn’t be petty. He was fully aware of it. He knew that starving Jason for not killing the masked vigilante he’d tossed in his tank wasn’t particularly fair. Especially not because he hadn't explained to Jason why he was punishing him. But Roman was angry about Batman’s interference and seeing Jason snarl and rage at him helped him feel better about life in general.

He told one of the men fed his pet to just give Jason a few fish. Jason killed the man and stole the whole bucket. Roman smiled. He was still his vicious pet. Roman ordered him to be resume being fed, but only fish that were already dead. He knew Jason preferred the hunt and the kill. The next guilty man he threw in his tank got a truly gruesome death.

Roman was beginning to feel good about things again and settle back into his business, and then-

Then he came into his office one night without bothering to turn on a light and noticed Jason was at the surface of his tank and his hatch was open. Roman frowned. Quietly he checked the security feeds from his phone. It showed nothing, but then it was also showing that Jason’s tank was tightly sealed as ever.

Someone had hacked his system.

Roman got his answer to who a moment later when Jason pulled a surprised Robin into the water with him. Jason went to give him a little air when Robin flushed and stopped him, instead fitting on a rebreather over his face. Roman had to will the rage down in his system and instead checked through the refreshed security for Batman, but the older vigilante was nowhere in sight. His partner however was swimming around with his pet. It looked like they were… _playing_. Robin swimming and trying to catch up while Jason swam circles around him, spun him, teased him.

Jason looked utterly fascinated at the tiny human in his tank.

Roman on the other hand was quickly developing a hatred for Robin.

He decided to wait and see what would happen though. Robin continued to visit every few nights. Sometimes they chatted at the opening of his tank (his pet apparently knew how to _talk_ and had a deep throaty voice that suited his personality) and sometimes they swam and played in the water. He watched with no small about of possessiveness as Robin eventually plucked up the courage to give Jason a shy kiss. As he explained to Jason what kisses _were_ , what they meant to humans. As he taught Jason how to kiss to the point where Jason always greeted him with an aggressive kiss that made Robin melt every time and let Jason pull him into the water.

He wasn’t overly surprised the first time the two fools had sex in the tank.

Roman had taken to sitting in the shadow of his desk and watching them. Robin wouldn’t be able to see him in the dark, but he knew Jason could. Jason wouldn’t know that Robin might not like him to see these things though. That he maybe should _mind_ that a human was watching him. Human’s were always watching Jason after all.

It was strangely erotic to watch the two species have sex. Robin- he learned- had a pale, thin, and pretty little body that looked especially nice next to Jason’s bulk. He learned that Jason liked to pin Robin down onto the sandy floor of the tank and demand submission in a way that was customary for Jason’s species.

He’s learned that Robin looked good with a thick pronged cock up his ass.

Jason’s learned that human’s need careful stretching after the first time where he hurt Robin. The idea that all humans don’t self-lubricate was doubtless startling to the Merman. The idea that blood and hurting during a mating was also not desired during a human mating almost equally so. Robin has learned to always wear a breathing mask because while Jason could breath air into him it doesn’t work all that great when he’s gaping and gasping at the sensations he’s feeling and he nearly drowned one time.

That was fun.

Roman enjoys how sloppy Jason makes Robin. Both physically- Roman has definitely now had some Thoughts™ about Robin’s ass and how it might feel to bend him over himself- and professionally. Robin is getting careless in his safety precautions, watching less attentively for security. He let’s Jason peal him out of his suit till he’s floating defenseless and vulnerable with the Merman. Roman’s thought about locking them in there and dumping the suit and it’s trackers into the Gotham River for Batman. But he hold’s off because Robin keeps letting slip information to Jason.

Things about what Batman’s been up to.

Occasionally a tip off of where he’ll be.

Robin’s name is start’s with a T. He started to tell Jason it but remembered himself the last second. Jason doesn’t care. Robin is his “little bird” and that’s all the Mer cares about.

Batman is apparently rich enough that creating an elaborate living space for Jason inland or getting him back to the Sea would be no problem.

The last one makes him grit his teeth. Jason can’t go back to the Sea, the Merfolk are vicious and would rip him to shreds as tame and unpracticed at fighting as he is. And Roman would never let anyone steal his pet from him, especially not to become Batman’s pet. If Robin ever looks like he’s going to move on trying to take Jason away, Roman’s going to teach him a painful lesson.

He’d rather not intterupt though till he has to. He’s continuing to gather usful information from Robin after all. And making Robin attached to his pet gives him excelent leverage over both him and Batman in the future. And he _certainly_ doesn’t mind the free porn he gets every other night.

Roman starts to dream of getting Jason under him. Of covering his sharp teeth and fucking that pretty mouth. Of hooking his fingers in that pretty opening of his and tormenting his viocious little pet till he’s slick and dripping. Maybe even extended. He dreams of sinking his own cock into that wet tight heat and fucking Jason till he’s crying out in that sweet deep voice of his.

Of course he knows it’d never work like that.

Jason would doubtless try and kill him if he ever got close enough to touch. The Merman does not make it a secret that he’d like to do just that. Roman could always strap him down again, but that’d be a waste of a lot of men and Jason wouldn’t be able to survive out of the water for long enough for Roman to enjoy fucking him. And there was no way Roman was going to go into the water where Jason was strongest. He’s never had the desire to have underwater sex no matter how blissful Robin looks.

Roman strokes at his desk with the tips of his fingers and thinks about touching him anyway.

He watches Robin stumble and clumsily put on his uniform crokedly and walk bow leggedly to the window. Jason watches too, looking deeply satisfied and and pleased with himself. Roman wonders if he should tell Jason that he can’t knock Robin up. Or, well, Robin could knock Jason up but Roman would never allow it. If Jason were ever to carry they’d be Roman’s, he’s already decided. He had no idea how the little freaks would turn out but they’d be valuable and indisbutbly belong to Roman.

But that’s all for a different day.

**Author's Note:**

> Anyone wants to expand on this one feel free! Hope you enjoyed.
> 
> Come bother me on [Tumblr!](https://wellthatjusthappend.tumblr.com/)


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